When a general dental implant is implanted into the jawbone, osteoblasts derived from the surrounding bone tissue differentiate into new bone tissue in an osteoconductive and osteoinductive healing process. The new bone tissue adheres closely to the implant surface, so that the osseointegration of the implant with the surrounding bone tissue occurs to resist masticatory forces.
In the healing mechanism of prior implants, which have been used for implantation up to now, when bleeding occurs due to damage resulting from implant surgery, blood is filled into the space between the implant and a drill groove. When the filled blood comes into contact with the implant surface, a plasma protein layer is immediately adsorbed onto the implant surface, and platelets rapidly adhere to the adsorbed plasma protein layer and, at the same time, are activated. Various growth factors and cytokines are released from the activated platelets, and fibrin clots are rapidly formed due to various actions to clog the bleeding blood vessels, while cells of treating inflammations are collected in the wound sites. A series of such processes occur within about 72 hours after damage. The blood clots serve to stop the bleeding by blocking the broken blood vessels from an external environment and to store the released grown factors and acts to provide a temporary substrate for cell migration such that various cells required for bone formation or the treatment of inflammations can migrate to sites to be treated. Then, an angiogenesis process and a fibrous tissue formation process progress over about 4 weeks, while granulation tissue is formed and help undifferentiated cells to differentiate into osteoblasts. Then, the osteoblasts differentiate and develop into bone cells to form woven bone. The time required up to the formation of the woven bone is known to be about 2 months. In the characteristics of the woven bone, the formation of the woven tissue is a phenomenon that abnormally rapidly occurs due to a wound, the histological structure thereof is irregular compared to that of normal bone tissue, and thus the bone density thereof is also relatively low. After the woven bone is formed, the bone cells thereof are replaced with lamella bone having hard bone tissue. As the woven bone is completely replaced with the lamella bone, the implant is connected with the surrounding bone tissue, while the deposition of bone on the implant is completed and osseointegration between the implant and the bone tissue is completed through a bone remodeling process, so that the implant performs functions under normal forces. The time required for adaptation to the implant is 2-4 months depending on persons.
Also, in the current stage, the time for the bone tissue adhered to the interface with the implant to reach a level capable of mastication is 3-5 months for the lower jaw and 6-8 months for the upper jaw. This is because the osseointegration of the implant occurs only through an osteoconductive healing process. This process is called a healing period, in which bone cells naturally undergo a healing process in a normal human body. During this healing period, external stimuli such as inflammations or occlusal forces to the inserted implant should be limited such that the adhesion of bone tissue to the implant can be successively achieved. For this reason, a patient cannot masticate food for a long period of time and must continue to maintain oral hygiene performance to prevent infections. Thus, to reduce the bone healing period, technology for rapidly differentiating the surrounding undifferentiated adult cells into bone cells have been studied and developed in various ways.
As already found in several worldwide papers, recombinant human bone morphogenic proteins (BMPs) function to stimulate bone formation by moving adult stem cells from a site far away from the surrounding of the implant into the implanted site by chemotaxis so as to differentiate into osteoblasts. Methods of medical surgery using such recombinant bone morphogenic proteins (BMPs) are applied used in a wide range of fields, one of which is implant surgery.